Biodegradable polymers, the production thereof and the use thereof for producing biodegradable moldings

ABSTRACT

Biodegradable polyether esters P1 obtainable by the reaction of a mixture consisting essentially of: (a1) a mixture essentiall) of 20 to 95 mol % adipic acid or ester-forming derivatives thereof or mixtures thereof, 5 to 80 mol % terephthalic acid or ester-forming derivatives thereof or mixtures thereof, and 0 to 5 mol % of a sulphonate group-containing compounds In which the sum of the individual mol percentages is 100; and (a2) a mixture of dihydroxy compounds consisting essentially of (a21) 15 to 99 mol % of a dihydroxy compound selected from the group consisting of C 2 -C 6  alkane diols and C 5 -C 10  cycloalkane diols; (a22) 85 to 0.2 mol % of an ether function-containing dihydroxy compound as in formula I HO—[(CH 2 ) n —O] m —H in which n is 2, 3 or 4 and m is a whole number from 2 to 250, or mixtures thereof, in which the molar ratio of (a1) to (a2) is in the range from 0.4:1 to 1.5:1 with the proviso that the polyether esters P1 have molar weight (M n ) in the range from 5,000 to 80,000 g/mol, a viscosity index in the range from 30 to 450 g/ml (measured in o-dichlorobenzole/phenol (weight ratio 50/50) at a concentration of 0.5 wt. % polyether esters P1 at a temperature of 25° C.) and a melting point in the range from 50 to 200° C., and with the further proviso that from 0.01 to 5 mol %, in relation to the molar quantity of the components (a) used of a compound D with at least three groups capable of ester formation are used to produce the polyether esters P1, and other biodegradable polymers and thermoplastic moulding compounds, process for their production and biodegradable mouldings, adhesives, foams and blends with starch obtainable from the polymers or moulding compounds of the invention.

This application is a division of Ser. No. 08/975,307 filed Nov. 20,1997, which is a continuation of Ser. No. 08/836,039 filed May 14, 1997,now abandoned.

The present invention relates to biodegradable polyether esters P1obtainable by reacting a mixture essentially comprising

(a1) a mixture essentially comprising

25-95 mol % of adipic acid or ester-forming derivatives thereof ormixtures thereof,

5-80 mol % of terephthaIic acid or ester-forming derivatives thereof ormixtures thereof, and

0-5 mol % of a compound containing sulfonate groups, where the total ofthe individual mole percentages is 100 mol %, and

(a2) a mixture of dihydroxy compounds essentially comprising

(a21) from 15 to 99.8 mol % of a dihydroxy compound selected from thegroup consisting of C₂-C₆-alkanediols and C₅-C₁₀-cycloalkanediols,

(a22) from 85 to 0.2 mol % of a dihydroxy compound containing etherfunctionalities of the formula I

HO—[(CH₂)_(n)—O]_(m)—H  I

where n is 2, 3 or 4 and m is an integer from 2 to 250, or mixturesthereof,

where the molar ratio of (a1) to (a2) is chosen in the range from 0.4:1to 1.5:1, with the proviso that the polyether ester P1 has a molecularweight (M_(n)) in the range from 5000 to 80,000 g/mol, a viscositynumber in the range from 30 to 450 g/ml (measured ino-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of0.5 % by weight of polyether ester P1 at 25° C.) and a melting point inthe range from 50 to 200° C., and with the further proviso that from 0to 5 mol %, based on the molar quantity of component (a1) employed, of acompound D with at least three groups capable of ester formation areemployed to prepare the polyether ester P1.

The invention furthermore relates to polymers and biodegradablethermoplastic molding compositions as claimed in the dependent claims,processes for the preparation thereof, the use thereof for producingbiodegradable moldings and adhesives, biodegradable moldings, foams andblends with starch obtainable from the polymers and molding compositionsaccording to the invention.

Polymers which are biodegradable, ie. decompose under environmentalinfluences in an appropriate and demonstrable time span have been knownfor some time. This degradation usually takes place by hydrolysis and/oroxidation, but predominantly by the action of microorganisms such asbacteria, yeasts, fungi and algae. Y.Tokiwa and T. Suzuki (Nature, 270,(1977) 76-78) describe the enzymatic degradation of aliphaticpolyesters, for example including polyesters based on succinic acid andaliphatic diols.

EP-A 565,235 describes aliphatic copolyesters containing [—NH—C(O)O—]groups (urethane units). The copolyesters of EP-A 565,235 are obtainedby reacting a prepolyester, which is obtained by reacting essentiallysuccinic acid and an aliphatic diol, with a diisocyanate, preferablyhexamethylene diisocyanate. The reaction with the diisocyanate isnecessary according to EP-A 565,235 because the polycondensation aloneresults only in polymers with molecular weights such that they displayunsatisfactory mechanical properties. A crucial disadvantage is the useof succinic acid or ester derivatives thereof to prepare thecopolyesters because succinic acid and derivatives thereof are costlyand are not available in adequate quantity on the market. In addition,the polyesters prepared using succinic acid as the only acid componentare degraded only extremely slowly.

WO 92/13020 discloses copolyether esters based on predominantly aromaticdicarboxylic acids, short-chain ether diol segments such as diethyleneglycol, long-chain polyalkylene glycols such as polyethylene glycol(PEG) and aliphatic diols, where at least 85 mol % of the polyester diolresidue comprise a terephthalic acid residue. The hydrophilicity of thecopolyester can be increased and the crystallinity can be reduced bymodifications such as incorporation of up to 2.5 mol % of metal salts of5-sulfoisophthalic acid. This is said in WO 92/13020 to make thecopolyesters biodegradable. However, a disadvantage of thesecopolyesters is that biodegradation by microorganisms was notdemonstrated, on the contrary only the behavior towards hydrolysis inboiling water was carried out.

According to the statements of Y.Tokiwa and T.Suzuki (Nature, 270 (1977)76-78 or J. of Appl. Polymer Science, 26 (1981) 441-448), it may beassumed that polyesters which are essentially composed of aromaticdicarboxylic acid units and aliphatic diols, such as PET (polyethyleneterephthalate) and PBT (polybutylene terephthalate), are notenzymatically degradable. This also applies to copolyesters andcopolyether esters which contain blocks composed of aromaticdicarboxylic acid units and aliphatic diols or ether diols.

Witt et al. (handout for a poster at the International Workshop of theRoyal Institute of Technology, Stockholm, Sweden, Apr. 21-23, 1994)described biodegradable copolyesters based on 1,3-propanediol,terephthalic ester and adipic or sebacic acid. A disadvantage of thesecopolyesters is that moldings produced therefrom, especially sheets,have inadequate mechanical properties.

It is an object of the present invention to provide polymers which aredegradable biologically, ie. by microorganisms, and which do not havethese disadvantages. The intention was, in particular, that the polymersaccording to the invention be preparable from known and low-cost monomerunits and be insoluble in water. It was furthermore the intention thatit be possible to obtain products tailored-for the desired usesaccording to the invention by specific modifications such as chainextension, incorporation of hydrophilic groups and groups having abranching action. The aim was moreover that the biodegradation bymicroorganisms should not be achieved at the expense of the mechanicalproperties in order not to restrict the number of applications.

We have found that this object is achieved by the polymers andthermoplastic molding compositions defined at the outset.

We have furthermore found processes for the preparation thereof, the usethereof for producing biodegradable moldings and adhesives, andbiodegradable moldings and adhesives obtainable from the polymers andmolding compositions according to the invention.

The polyether esters P1 according to the invention have a molecularweight (M_(n)) in the range from 5000 to 80,000, preferably from 6000 to45,000, particularly preferably from 8000 to 35,000, g/mol, a viscositynumber in the range from 30 to 450, preferably from 50 to 400, g/ml(measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at aconcentration of 0.5% by weight of polyether ester P1 at 25 C.) and amelting point in the range from 50 to 200, preferably from 60 to 160° C.

The polyether esters P1 are obtained according to the invention byreacting a mixture essentially comprising

(a1) a mixture essentially comprising

20-95, preferably from 30 to 80, particularly preferably from 40 to 70mol % of adipic acid or ester-forming-derivatives thereof, in particularthe di-C₁-C₆-alkyl esters such as dimethyl, diethyl, dipropyl, dibutyl,diisobutyl, dipentyl and dihexyl adipate, or mixtures thereof,preferably adipic acid and dimethyl adipate, or mixtures thereof,

5-80, preferably 20-70, particularly preferably from 30 to 60mol % ofterephthalic acid or ester-forming derivatives thereof, in particularthe di-C₁-C₆-alkyl esters such as dimethyl, diethyl, dipropyl, dibutyl,dipentyl or dihexyl terephthalate, or mixtures thereof, preferablyterephthalic acid and dimethyl terephthalate, or mixtures thereof, and

0-5, preferably from 0 to 3, particularly preferably from 0.1 to 2, mol% of a compound containing sulfonate groups,

where the total of the individual mole percentages is 100 mol %, and

(a2) a mixture of dihydroxy compounds essentially comprising

(a21) from 15 to 99.8, preferably from 60 to 99.5, particularlypreferably from 70 to 99.5, mol % of a dihydroxy compound selected fromthe group consisting of C₂-C₆-alkanediols and C₅-C₁₀-cycloalkanediols,

(a22) from 85 to 0.2, preferably from 0.5 to 40, particularly preferablyfrom 0.5 to 30, mol % of a dihydroxy compound containing etherfunctionalities of the formula I

HO—[(CH₂)_(n)—O]_(m)—H  I

where n is 2, 3 or 4, preferably two and three, particularly preferablytwo, and m is an integer from 2 to 250, preferably from two to 100, ormixtures thereof,

where the molar ratio of (a1) to (a2) is chosen in the range from 0.4:1to 1.5:1, preferably from 0.6:1 to 1.25:1.

The compound containing sulfonate groups which is normally employed isan alkali metal or alkaline earth metal salt of a dicarboxylic acidcontaining sulfonate groups, or the ester-forming derivatives thereof,preferably alkali metal salts of 5-sulfoisophthalic acid or mixturesthereof, particularly preferably the sodium salt.

The dihydroxy compounds (a21) employed according to the invention areselected from the group consisting of C₂-C₆-alkanediols andC₅-C₁₀-cycloalkanediols, such as ethylene glycol, 1,2- and1,3-propanediol, 1,2- and 1,4-butanediol, 1,5-pentanediol or1,6-hexanediol, in particular ethylene glycol, 1,3-propanediol and1,4-butanediol, cyclopentanediol, cyclohexanediol,1,2-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, particularlypreferably ethylene glycol and 1,4-butanediol, and mixtures thereof.

The dihydroxy compounds (a22) which are preferably employed arediethylene glycol, triethylene glycol, polyethylene glycol,polypropylene glycol and polytetrahydrofuran (poly-THF), particularlypreferably diethylene glycol, triethylene glycol and polyethyleneglycol, it also being possible to employ mixtures thereof or compoundswhich have different n's (see formula I), for example polyethyleneglycol which contains propylene units (n=3) for example obtainable bypolymerization by conventional methods of initially ethylene oxide andsubsequently with propylene oxide, particularly preferably a polymerbased on polyethylene glycol with different n's, where units formed fromethylene oxide predominate. The molecular weight (M_(n)) of thepolyethylene glycol is usually chosen in the range from 250 to 8000,preferably from 600 to 3000, g/mol.

From 0 to 5, preferably from 0.01 to 4 mol %, particularly preferablyfrom 0.05 to 4, mol %, based on component (a1), of at least one compoundD with at least three groups capable of ester formation are usedaccording to the invention.

The compounds D preferably contain three to ten functional groupscapable of forming ester linkages. Particularly preferred compounds Dhave three to six functional groups of this type in the molecule, inparticular three to six hydroxyl groups and/or carboxyl groups. Exampleswhich may be mentioned are:

tartaric acid, citric acid, malic acid;

trimethylolpropane, trimethylolethane;

pentaerythritol;

polyethertriols;

glycerol;

trimesic acid;

trimellitic acid or anhydride;

pyromellitic acid or dianhydride and

hydroxyisophthalic acid.

When compounds D which have a boiling point below 200° C. are used inthe preparation of the polyesters P1, a proportion may distil out of thepolycondensation mixture before the reaction. It is therefore preferredto add these compounds in an early stage of the process, such as thetransesterification or esterification stage, in order to avoid thiscomplication and in order to achieve the maximum possible uniformity oftheir distribution within the polycondensate.

In the case of compounds D which boil above 200° C., they can also beemployed in a later stage of the process.

By adding the compound D it is possible, for example, to alter the meltviscosity in a desired manner, to increase the impact strength and toreduce the crystallinity of the polymers or molding compositionsaccording to the invention.

The preparation of the biodegradable polyether esters P1 is known inprinciple (Sorensen and Campbell, Preparative Methods of PolymerChemistry, Interscience Publishers, Inc., New York, 1961, pages 111-127;Encyl. of Polym. Science and Eng., Vol. 12, 2nd Edition, John Wiley &Sons, 1988, pages 75-117; Kunststoff-Hand-buch, Volume 3/1, Carl HanserVerlag, Munich, 1992, pages 15-23 (Preparation of Polyesters); WO92/13020; EP-A 568 593; EP-A 565 235; EP-A 28 687) so that details onthis are superfluous.

Thus, for example, the reaction of dimethyl esters of component (a1)with component (a2) (transesterification) can be carried out at from 160to 230 ° C. in the melt under atmospheric pressure, advantageously underan inert gas atmosphere.

In the preparation of the biodegradable polyether ester P1 it isadvantageous to use a molar excess of component (a2) relative tocomponent (a1), for example up to 2½ times, preferably up to 1.67 times.

The biodegradable polyether ester P1 is normally prepared with additionof suitable conventional catalysts such as metal compounds based on thefollowing elements such as Ti, Ge, Zn, Fe, Mn, Co, Zr, V, Ir, La, Ce,Li, and Ca, preferably organometallic compounds based on these metals,such as salts of organic acids, alkoxides, acetylacetonates and thelike, particularly preferably based on zinc, tin and titanium.

When dicarboxylic acids or anhydrides thereof are used as component(a1), esterification thereof with component (a2) can take place before,at the same time as or after the transesterification. For example, theprocess described in DE-A 23 26 026 for preparing modified polyalkyleneterephthalates can be used.

After the reaction of components (a1) and (a2), the polycondensation iscarried out as far as the desired molecular weight, as a rule underreduced pressure or in a stream of inert gas, for example of nitrogen,with further heating to from 180 to 260° C.

In order to prevent unwanted degradation and/or side reactions, it isalso possible in this stage of the process if required to addstabilizers (see EP-A 21 042 and US-A 4 321 341). Examples of suchstabilizers are the phosphorus compound described in EP-A 13 461, US 4328 049 or in B. Fortunato et al., Polymer Vol. 35, No. 18, pages4006-4010, 1994, Butterworth-Heinemann Ltd. These may also in some casesact as inactivators of the catalysts described above. Examples which maybe mentioned are: organophosphites, phosphonous acid and phosphorousacid. Example of compounds which act only as stabilizers are: trialkylphosphites, triphenyl phosphite, trialkyl phosphates, triphenylphosphate and tocopherol (obtainable as Uvinul^(R) 2003AO (BASF) forexample).

On use of the biodegradable copolymers according to the invention, forexample in the packaging sector, eg. for foodstuffs, it is as a ruledesirable to select the lowest possible content of catalyst employed andnot to employ any toxic compounds. In contrast to other heavy metalssuch as lead, tin, antimony, cadmium, chromium, etc., titanium and zinccompounds are non-toxic as a rule (Sax Toxic Substance Data Book, ShizuoFujiyama, Maruzen, K. K., 360 S. (cited in EP-A 565,235), see also RomppChemie Lexikon Vol. 6, Thieme Verlag, Stuttgart, New York, 9th Edition,1992, pages 4626-4633 and 5136-5143). Examples which may be mentionedare: dibutoxydiacetoacetoxytitanium, tetrabutyl orthotitanate andzinc(II) acetate.

The ratio by weight of catalyst to biodegradable polyether ester P1 isnormally in the range from 0.01:100 to 3:100, preferably from 0.05:100to 2:100, it also being possible to employ smaller quantities, such as0.0001:100, in the case of highly active titanium compounds.

The catalyst can be employed right at the start of the reaction,directly shortly before the removal of the excess diol or, if required,also distributed in a plurality of portions during the preparation ofthe biodegradable polyether esters P1. It is also possible if requiredto employ different catalysts or mixtures thereof.

The biodegradable polyether esters P2 according to the invention have amolecular weight (M_(n)) in the range from 5000 to 80,000, preferablyfrom 6000 to 45,000, particularly preferably from 10,000 to 40,000,g/mol, a viscosity number in the range from 30 to 450, preferably from50 to 400, g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio byweight) at a concentration of 0.5% by weight of polyether ester P2 at25° C.) and a melting point in the range from 50 to 235, preferably from60 to 235° C.

The biodegradable polyether esters P2 are obtained according to theinvention by reacting a mixture essentially comprising

(b1) a mixture essentially comprising

20-95, preferably from 25 to 80, particularly preferably from 30 to 70,molts of adipic acid or ester-forming derivatives thereof or mixturesthereof,

5-80, preferably from 20 to 75, particularly preferably from 30 to 70,mol % of terephthalic acid or ester-forming derivatives thereof ormixtures thereof, and

0-5, preferably from 0 to 3, particularly preferably from 0.1 to 2, mol% of a compound containing sulfonate groups,

where the total of the individual mole percentages is 100 mol %,

(b2) a mixture of dihydroxy compounds (a2),

where the molar ratio of (b1) to (b2) is chosen in the range from 0.4:1to 1.25:1, preferably from 0.6:1 to 1.25:1,

(b3) from 0.01 to 100, preferably from 0.1 to 80, % by weight, based oncomponent (b1), of a hydroxy carboxylic acid B1, and

(b4) from 0 to 5, preferably from 0 to 4, particularly preferably from0.01 to 3.5, mol %, based on component (b1), of compound D,

where the hydroxy carboxylic acid B1 is defined by the formulae IIa orIIb

where p is an integer from 1 to 1500, preferably from 1 to 1000, and ris 1, 2, 3 or 4, preferably 1 and 2, and G is a radical selected fromthe group consisting of phenylene, —(CH2)k—, where k is an integer from1, 2, 3, 4 or 5, preferably 1 and 5, —C(R)H—and —C(R)HCH₂, where R ismethyl or ethyl.

The biodegradable polyether esters P2 are espediently prepared in asimilar way to the preparation of the polyether esters P1, it beingpossible to add the hydroxy carboxylic acid B1 both at the start of thereaction and after the esterification or transesterification stage.

In a preferred embodiment, the hydroxy carboxylic acid B1 such asglycolic acid, D-, L- or D,L-lactic acid, 6-hydroxyhexanoic acid, thecyclic derivates thereof such as glycolide (1,4-dioxane2,5-dione), D- orL-dilactide (3,6-dimethyl-1,4-dioxane2,5-dione), p-hydroxybenzoic acidand oligomers and polymers such as poly-3-hydroxybutyric acid,polyhydroxyvaleric acid, polylactide (obtainable as EcoPLA® (fromCargill) for example) and a mixture of poly-3-hydroxybutyric acid andpolyhydroxyvaleric acid (obtainable under the name Biopol® from zenecafor example), the low molecular weight and cyclic derivatives thereofare particularly preferably employed for preparing polyether esters P2.

The biodegradable polyether esters Q1 according to the invention have amolecular weight (M_(n)) in the range from 5000 to 100,000, preferablyfrom 8000 to 80,000, a viscosity number in the range from 30 to 450,preferably from 50 to 400 g/ml (measured in o-dichlorobenzene/phenol(50/50 ratio by weight) at a concentration of 0.5% by weight ofpolyether ester Q1 at 25° C.), and a melting point in the range from 50to 235, preferably from 60 to 235° C.

The polyether esters Q1 are obtained according to the invention byreacting a mixture essentially comprising

(c1) polyether ester P1,

(c2) 0.01-50, preferably from 0.1 to 40, % by weight, based on (c1), ofhydroxy carboxylic acid B1 and

(c3) 0-5, preferably from 0 to 4, mol %, based on component (a1) fromthe preparation of P1, of compound D.

The reaction of the polyether esters P1 with the hydroxy carboxylic acidB1, if required in the presence of compound D, preferably takes place inthe melt at from 120 to 260° C. under an inert gas atmosphere, ifdesired also under reduced pressure. The procedure can be both batchwiseand continuous, for example in stirred vessels or (reaction) extruders.

The reaction rate can, if required, be increased by adding conventionaltransesterification catalysts (see those described hereinbefore for thepreparation of the polyether esters P1).

A preferred embodiment relates to polyether esters Q1 with blockstructures formed from components P1 and B1: when cyclic derivatives ofB1 (compounds IIb) are used it is possible in the reaction with thebiodegradable polyether ester P1 to obtain, by a ring-openingpolymerization initiated by the end groups of P1, in a conventional waypolyether esters Q1 with block structures (on the ring-openingpolymerization, see Encycl. of Polym. Science and Eng. Volume 12, 2ndEdition, John Wiley & Sons, 1988, pages 1-75, in particular pages36-41). The reaction can, if required, be carried out with addition ofconventional catalysts like the transesterification catalysts describedhereinbefore, and tin octanoate is particularly preferred (see alsoEncycl. of Polym. Science and Eng. Volume 12, 2nd Edition, John Wiley &Sons, 1988, pages 1-75, in particular pages 36-41).

When components B1 with higher molecular weights, for example with a pabove 10 (ten) are used, it is possible to obtain, by reaction with thepolyether esters P1 in stirred vessels or extruders, the desired blockstructures by the choice of the reaction conditions such as temperature,holdup time, addition of transesterification catalysts such as theabovementioned. Thus, J. of Appl. Polym. Sci., 32 (1986) 6191-6207 andMakromol. Chemie, 136 (1970) 311-313 disclose that in the reaction ofpolyether esters in the melt it is possible to obtain from a blend bytransesterification reactions initially block copolymers and then randomcopolymers.

The biodegradable polyether esters Q2 according to the invention have amolecular weight (M_(n)) in the range from 6000 to 80,000, preferablyfrom 8000 to 50,000, particularly preferably from 10,000 to 40,000g/mol, a viscosity number in the range from 30 to 450, preferably from50 to 400 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio byweight) at a concentration of 0.5% by weight of polyether ester Q2 at25° C.), and a melting point in the range from 50 to 200° C., preferablyfrom 60 to 160° C.

The polyether esters Q2 are obtained according to the invention byreacting a mixture essentially comprising

(d1) from 95 to 99.9, preferably from 96 to 99.8, particularlypreferably from 97 to 99.65, % by weight of polyether ester P1,

(d2) from 0.1 to 5, preferably 0.2-4, particularly preferably from 0.35to 3, % by weight of a diisocyanate C1 and

(d3) from 0 to 5, preferably from 0 to 4, mol %, based on component (a1)from the preparation of P1, of compound D.

It is possible according to observations to date to employ asdiisocyanate C1 all conventional and commercially obtainablediisocyanates. A diisocyanate which is selected from the groupconsisting of tolylene 2,4-diisocyanate, tolylene 2,6-diisocyanate,4,4′- and 2,4′-diphenylmethane diisocyanate, naphthylene1,5-diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate,isophorone diisocyanate and methylenebis(4-isocyanatocyclohexane),particularly preferably hexamethylene diisocyanate, is preferablyemployed.

It is also possible in principle to employ trifunctional isocyanatecompounds which may contain isocyanurate and/or biuret groups with afunctionality of not less than three, or to replace the diisocyanatecompounds C1 partially by tri- or polyisocyanates.

The polyether esters P1 are reacted with the diisocyanate C1 preferablyin the melt, it being necessary to take care that, if possible, no sidereactions which may lead to crosslinking or gel formation occur. In aparticular embodiment, the reaction is normally carried out at from 130to 240, preferably from 140 to 220° C., with the addition of thediisocyanate advantageously taking place in a plurality of portions orcontinuously.

If required it is also possible to carry out the reaction of thepolyether ester P1 with the diisocyanate C1 in the presence ofconventional inert solvents such as toluene, methyl ethyl ketone ordimethylformamide (DMF) or mixtures thereof, in which case the reactionis as a rule carried out at from 80 to 200, preferably from 90 to 150°C.

The reaction with the diisocyanate C1 can be carried out batchwise orcontinuously, for example in stirred vessels, reaction extruders orthrough mixing heads.

It is also possible to employ in the reaction of the polyether esters P1with the diisocyanates C1 conventional catalysts which are disclosed inthe prior art (for example those described in EP-A 534 295) or which canbe or have been used in the preparation of the polyether esters P1 andQ1 and, if the polyether esters P1 have not been isolated in thepreparation of polyether ester Q2, can now be used further.

Examples which may be mentioned are: tertiary amines such astriethylamine, dimethylcyclohexylamine, N-methylmorpholine,N,N′-dimethylpiperazine, diazabicyclo[2.2.2]octane and the like and, inparticular, organic metal compounds such as titanium compounds, ironcompounds, tin compounds, eg. dibutoxydiacetoacetoxytitanium, tetrabutylorthotitanate, tin diacetate, dioctoate, dilaurate or the dialkyltinsalts of aliphatic carboxylic acids such as dibutyltin diacetate,dibutyltin dilaurate or the like, it again being necessary to take carethat, if possible, no toxic compounds ought to be employed.

Although the theoretical optimum for the reaction of P1 withdiisocyanates C1 is a 1:1 molar ratio of isocyanate functionality to P1end group (polyether esters P1 with mainly hydroxyl end groups arepreferred), the reaction can also be carried out without technicalproblems at molar ratios of from 1:3 to 1.5:1. With molar ratios of >1:1it is possible if desired to add, during the reaction or else after thereaction, a chain extender selected from the components (a2), preferablya C₂-C₆-diol.

The biodegradable polymers T1 according to the invention have amolecular weight (M_(n)) in the range from 10,000 to 100,000, preferablyfrom 11,000 to 80,000, preferably from 11,000 to 50,000, g/mol, aviscosity number in the range from 30 to 450, preferably from 50 to 400,g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) at aconcentration of 0.5% by weight of polymer T1 at 25° C.) and a meltingpoint in the range from 50 to 235, preferably from 60 to 235° C.

The biodegradable polymers T1 are obtained according to the invention byreacting a polyether ester Q1 as claimed in claim 3 with

(e1) 0.1-5, preferably from 0.2 to 4, particularly preferably from 0.3to 3, % by weight, based on the polyether ester Q1, of diisocyanate C1and with

(e2) 0-5, preferably from 0 to 4 mol %, based on component (a1) from thepreparation of P1 and polyether ester Q1, of compound D.

This normally results in a chain extension, with the resulting polymerchains preferably having a block structure.

The reaction is, as a rule, carried out in a similar way to thepreparation of the polyether esters Q2.

The biodegradable polymers T2 according to the invention have amolecular weight (M_(n)) in the range from 10,000 to 100,000, preferablyfrom 11,000 to 80,000, particularly preferably from 11,000 to 50,000g/mol, a viscosity number in the range from 30 to 450, preferably from50 to 400 g/ml (measured in o-dichlorobenzene/phenol (50/50 ratio byweight) at a concentration of 0.5% by weight of polymer T2 at 25° C.)and a melting point in the range from 50 to 235, preferably from 60 to235° C.

The biodegradable polymers T2 are obtainable according to the inventionby reacting the polyether ester Q2 with

(f1) 0.01-50, preferably from 0.1 to 40, % by weight, based on thepolyether ester Q2, of the hydroxy carboxylic acid B1 and with

(f2) 0-5, preferably from 0 to 4, mol %, based on component (a1) fromthe preparation of polyether ester Q2 via the polyether ester P1, ofcompound D,

the procedure expediently being similar to the reaction of polyetherester P1 with hydroxy carboxylic acid B1 to give polyether ester Q1.

The biodegradable polymers T3 according to the invention have amolecular weight (M_(n)) in the range from 10,000 to 100,000, preferablyfrom 11,000 to 80,000 g/mol, a viscosity number in the range from 30 to450, preferably from 50 to 400 g/ml (measured ino-dichlorobenzene/phenol (50/50 ratio by weight) at a concentration of0.5% by weight of polymer T3 at 25° C.) and a melting point in the rangefrom 50 to 235, preferably from 60 to 235° C.

The biodegradable polymers T3 are obtained according to the in10 ventionby reacting (g1) polyether ester P2, or (g2) a mixture essentiallycomprising polyether ester P1 and 0.01-50, preferably from 0.1 to 40, %by weight, based on the polyether ester P1, of hydroxy carboxylic acidB1, or (g3) a mixture essentially comprising polyether esters P1 whichdiffer from one another in composition, with

0.1-5, preferably from 0.2 to 4, particularly preferably from 0.3 to2.5, %, by weight, based on the quantity of polyether esters employed,of diisocyanate C1 and

with 0-5, preferably from 0 to 4, mol %, based on the respective molarquantities of component (a1) employed to prepare the polyether esters(g1) to (g3) employed, of compound D, expediently carrying out thereactions in a similar way to the preparation of the polyether esters Q2from the polyether esters P1 and the diisocyanates C1.

In a preferred embodiment, polyether esters P2 whose repeating units arerandomly distributed in the molecule are employed.

However, it is also possible to employ polyether esters P2 whose polymerchains have block structures. Polyether esters P2 of this type cangenerally be obtained by appropriate choice, in particular of themolecular weight, of the hydroxy carboxylic acid B1. Thus, according toobservations to date there is generally only incompletetransesterification when a high molecular weight hydroxy carboxylic acidB1 is used, in particular with a p above 10, for example even in thepresence of the inactivators described above (see J. of Appl. Polym.Sci. 32 (1986) 6191-6207 and Makromol. Chemie, 136 (1970) 311-313). Ifrequired, the reaction can also be carried out in solution using thesolvents mentioned for the preparation of the polymers T1 from thepolyether esters Q1 and the diisocyanates C1.

The biodegradable thermoplastic molding compositions T4 are obtainedaccording to the invention by mixing in a conventional way, preferablywith the addition of conventional additives such as stabilizers,processing aids, fillers etc. (see J. of Appl. Polym. Sci., 32 (1986)6191-6207; WO 92/0441; EP 515,203; Kunststoff-Handbuch, Vol. 3/1, CarlHanser Verlag Munich, 1992, pages 24-28)

(h1) 99.5-0.5% by weight of polyether ester P1 as claimed in claim 1 orpolyether ester Q2 as claimed in claim 4 with

(h2) 0.5-99.5% by weight of hydroxy carboxylic acid B1.

In a preferred embodiment, high molecular weight hydroxy carboxylicacids B1 such as polycaprolactone or polylactide (eg. EcoPLA®) orpolyglycolide or polyhydroxyalkanoates such as poly-3- hydroxybutyricacid, polyhydroxyvaleric acid and mixtures thereof (eg. Biopol®) with amolecular weight (M_(n)) in the range from 10,000 to 150,000, preferablyfrom 10,000 to 100,000, g/mol are employed.

WO 92/0441 and EP-A 515 203 disclose that high molecular weightpolylactide without added plasticizers is too brittle for mostapplications. It is possible in a preferred embodiment to prepare ablend starting from 0.5-20, preferably from 0.5 to 10, % by weight ofpolyether ester P1 as claimed in claim 1 or polyether ester Q2 asclaimed in claim 4 and

99.5-80, preferably from 99.5 to 90, % by weight of polylactide, whichdisplays a distinct improvement in the mechanical properties, forexample an increase in the impact strength, compared with purepolylactide.

Another preferred embodiment relates to a blend obtainable by mixing

from 99.5 to 40, preferably from 99.5 to 60, % by weight of polyetherester P1 as claimed in claim 1 or polyether ester Q2 as claimed in claim4 and

from 0.5 to 60, preferably from 0.5 to 40, % by weight of a highmolecular weight hydroxy carboxylic acid B1, particularly preferablypolylactide (eg. EcoPLA®), polyglycolide, poly-3-hydroxybutyric acid,polyhydroxyvaleric acid and mixtures thereof (eg. Biopol®), andpolycaprolactone. Blends of this type are completely biodegradable and,according to observations to date, have very good mechanical properties.

According to observations to date, the thermoplastic moldingcompositions T4 according to the invention are preferably obtained byobserving short mixing times, for example when carrying out the mixingin an extruder. It is also possible to obtain molding compositions whichhave predominantly blend structures by choice of the mixing parameters,in particular the mixing time and, if required, the use of inactivators,ie. it is possible to control the mixing process so thattransesterification reactions can also take place at least partly.

In another preferred embodiment it is possible to replace 0-50,preferably 0-30, mol % of the adipic acid or the ester-formingderivatives thereof or the mixtures thereof by at least one otheraliphatic C₄-C₁₀- or cycloaliphatic C₅-C₁₀-dicarboxylic acid or dimerfatty acids such as succinic acid, glutaric acid, pimelic acid, subericacid, azelaic acid or sebacic acid or an ester derivate such as thedi-C₁-C₆-alkyl esters thereof or the anhydrides thereof such as succinicanhydride, or mixtures thereof, preferably succinic acid, succinicanhydride, sebacic acid, dimer fatty acid and di-C₁-C₆-alkyl esters suchas dimethyl, diethyl, di-n-propyl, diisobutyl, di-n-pentyl, dineopentyl,di-n-hexyl esters thereof, especially dimethyl succinate.

A particularly preferred embodiment relates to the use as component (a1)of the mixture, described in EP-A 7445, of succinic acid, adipic acidand glutaric acid and the C₁-C₆-alkyl esters thereof such as dimethyl,diethyl, di-n-propyl, diisobutyl, di-n-pentyl, dineopentyl, di-n-hexylesters, especially the dimethyl esters and diisobutyl esters thereof.

In another preferred embodiment it is possible to replace 0-50,preferably 0-40, mol % of the terephthalic acid or the ester-formingderivatives thereof, or the mixtures thereof, by at least one otheraromatic dicarboxylic acid such as isophthalic acid, phthalic acid or2,6-naphthalenedicarboxylic acid, preferably isophthalic acid, or anester derivative such as a di-C₁-C₆-alkyl ester such as dimethyl,diethyl, di-n-propyl, diisobutyl, di-n-pentyl, dineopentyl, di-n-hexylester, in particular a dimethyl ester, or mixtures thereof.

It should be noted in general that the various polymers according to theinvention can be worked up in a conventional way by isolating thepolymers or, in particular if it is wished to react the polyether estersP1, P2, Q1 and Q2 further, by not isolating the polymers but immediatelyprocessing them further.

The polymers according to the invention can be applied to coatingsubstrates by rolling, spreading, spraying or pouring. Preferred coatingsubstrates are those which are compostable or rot such as moldings ofpaper, cellulose or starch.

The polymers according to the invention can also be used to producemoldings which are compostable. Moldings which may be mentioned by wayof example are: disposable articles such as crockery, cutlery, refusesacks, sheets for agriculture to advance harvesting, packaging sheetsand vessels for growing plants.

It is furthermore possible to spin the polymers according to theinvention into threads in a conventional way. The threads can, ifrequired, be stretched, stretch-twisted, stretch-wound, stretch-warped,stretch-sized and stretch-texturized by customary methods. Thestretching to flat yarn can moreover take place in the same working step(fully drawn yarn or fully oriented yarn) or in a separate step. Thestretch warping, stretch sizing and stretch texturizing are generallycarried out in a working step separate from the spinning. The threadscan be further processed to fibers in a conventional way. Sheet-likestructures can then be obtained from the fibers by weaving or knitting.

The moldings, coating compositions and threads etc. described above can,if required, also contain fillers which can be incorporated during thepolymerization process at any stage or subsequently, for example in themelt of the polymers according to the invention.

It is possible to add from 0 to 80% by weight of fillers, based on thepolymers according to the invention. Examples of suitable fillers arecarbon black, starch, lignin powder, cellulose fibers, natural fiberssuch as sisal and hemp, iron oxides, clay minerals, ores, calciumcarbonate, calcium sulfate, barium sulfate and titanium dioxide. Thefillers can in some cases also contain stabilizers such as tocopherol(vitamin E), organic phosphorus compounds, mono-, di- and polyphenols,hydroquinones, diarylamines, thioethers, UV stabilizers, nucleatingagents such as talc, and lubricants and mold release agents based onhydrocarbons, fatty alcohols, higher carboxylic acids, metal salts ofhigher carboxylic acids such as calcium and zinc stearate, and montanwaxes. Such stabilizers etc. are described in detail inKunststoff-Handbuch, Vol. 3/1, Carl Hanser Verlag, Munich, 1992, pages24-28.

The polymers according to the invention can additionally be colored inany desired way by adding organic or inorganic dyes. The dyes can alsoin the widest sense be regarded as filler.

A particular application of the polymers according to the inventionrelates to the use as compostable sheet or a compostable coating asouter layer of diapers. The outer layer of the diapers effectivelyprevents penetration by liquids which are absorbed inside the diaper bythe fluff and superabsorbers, preferably by biodegradablesuperabsorbers, for example based on crosslinked polyacrylic acid orcrosslinked polyacrylamide. It is possible to use a web of a cellulosematerial as inner layer of the diaper. The outer layer of the describeddiapers is biodegradable and thus compostable. It disintegrates oncomposting so that the entire diaper rots, whereas diapers provided withan outer layer of, for example, polyethylene cannot be composted withoutprevious reduction in size or elaborate removal of the polyethylenesheet.

Another preferred use of the polymers and molding compositions accordingto the invention relates to the production of adhesives in aconventional way (see, for example, Encycl. of Polym. Sc. and Eng. Vol.1, “Adhesive Compositions”, pages 547-577). The polymers and moldingcompositions according to the invention can also be processed asdisclosed in EP-A 21042 using suitable tackifying thermoplastic resins,preferably natural resins, by the methods described therein. Thepolymers and molding compositions according to the invention can also befurther processed as disclosed in DE-A 4 234 305 to solvent-freeadhesive systems such as hot melt sheets.

Another preferred application relates to the production of completelydegradable blends with starch mixtures (preferably with thermoplasticstarch as described in WO 90/05161) in a similar process to thatdescribed in DE-A 42 37 535. The polymers according to the invention canin this case be mixed both as granules and as polymer melts with starchmixtures, and admixing as polymer melt is preferred because this allowsone process step (granulation) to be saved (direct finishing). Thepolymers and thermoplastic molding compositions according to theinvention can, according to observations to date, because of theirhydrophobic nature, their mechanical properties, their completebiodegradability, their good compatibility with thermoplastic starch andnot least because of their favorable raw material basis, advantageouslybe employed as synthetic blend component.

Further applications relate, for example, to the use of the polymersaccording to the invention in agricultural mulch, packaging material forseeds and nutrients, substrate in adhesive sheets, baby pants, pouches,bed sheets, bottles, boxes, dust bags, labels, cushion coverings,protective clothing, hygiene articles, handkerchiefs, toys and wipes.

Another use of the polymers and molding compositions according to theinvention relates to the production of foams, generally by conventionalmethods (see EP-A 372 846; Handbook of Polymeric foams and FoamTechnology, Hanser Publisher, Munich, 1991, pages 375-408). Thisnormally entails the polymer or molding composition according to theinvention being initially melted, if required with the addition of up to5% by weight of compound D, preferably pyromellitic dianhydride andtrimellitic anhydride, then a blowing agent being added and theresulting mixture being exposed to reduced pressure by extrusion,resulting in foaming.

The advantages of the polymers according to the invention over knownbiodegradable polymers are a favorable raw material basis with readilyavailable starting materials such as adipic acid, terephthalic acid andconventional diols, interesting mechanical properties due to thecombination of “hard” (owing to the aromatic dicarboxylic acids such asterephthalic acid) and “soft” (owing to the aliphatic dicarboxylic acidssuch as adipic acid) segments in the polymer chain and the variation inuses due to simple modifications, a satisfactory degradation bymicroorganisms, especially in compost and soil, and a certain resistanceto microorganisms in aqueous systems at room temperature, which isparticularly advantageous for many applications. The randomincorporation of the aromatic dicarboxylic acids of component (a1) invarious polymers makes the biological attack possible and thus achievesthe desired biodegradability.

A particular advantage of the polymers according to the invention isthat it is possible by tailoring the formulations to optimize both thebiodegradation and the mechanical properties for the particularapplication.

It is furthermore possible depending on the preparation processadvantageously to obtain polymers with predominantly random distributionof monomer units, polymers with predominantly block structures andpolymers with predominantly blend structure or blends.

EXAMPLES Enzyme test

The polymers were cooled with liquid nitrogen or dry ice and finelyground in a mill (the rate of enzymatic breakdown increases with thesurface area of the milled material). To carry out the actual enzymetest, 30 mg of finely ground polymer powder and 2 ml of a 20 mmol/laqueous K₂HPO₄/KH₂PO₄ buffer solution (pH: 7.0) were placed in anEppendorf tube (2 ml) and equilibrated at 37° C. in a tube rotator for 3h. Subsequently 100 units of lipase from either Rhizopus arrhizus,Rhizopus delemar or Pseudomonas p1. were added, and the mixture wasincubated at 37° C. while agitating (250 rpm) on the tube rotator for 16h. The reaction mixture was then filtered through a Millipore® membrane(0.45 μm), and the DOC (dissolved organic carbon) of the filtrate wasmeasured. A DOC measurement was carried out with only buffer and enzyme(as enzyme control) and with only buffer and sample (as blank) in asimilar way.

The determined ΔDOC values (DOC (sample+enzyme)-DOC (enzyme control)-DOC(blank)) can be regarded as a measure of the enzymatic degradability ofthe samples. They are represented in each case by comparison with ameasurement with a powder of Polycapro lactone® Tone P 787 (UnionCarbide). It should be noted in the assessment that these ΔDOC valvesare not absolutely quantifiable data. Mention has already been madehereinbefore of the connection between the surface area of the milledmaterial and the rate of enzymatic degradation. Furthermore, theenzymatic activities may also vary.

The hydroxyl number (OH number) and acid number (AN) were determined bythe following methods:

(a) Determination of the apparent hydroxyl number 10 ml of toluene and9.8 ml of acetylating reagent (see below) were added to about 1 to 2 gof accurately weighed test substance, and the mixture was heated withstirring at 95° C. for 1 h. Then 5 ml of distilled water were added.After cooling to room temperature, 50 ml of tetrahydrofuran (THF) wereadded, and the mixture was titrated to the turning point againstethanolic KOH standard solution using a potentiograph.

The experiment was repeated without test substance (blank sample).

The apparent OH number was then determined from the following formula:

apparent OH number c×t×56.1×(V2−V1)/m(in mg KOH/g)

where c=amount of substance concentration of the ethanolic KOH standardsolution in mol/l,

t=titer of the ethanolic KOH standard solution

m=weight of test substance in mg

V1=ml of standard solution used with test substance

V2=ml of standard solution used without test substance.

Reagents used:

ethanolic KOH standard solution, c=0.5 mol/l, titer 0.9933 (Merck, Cat.No. 1.09114)

acetic anhydride, analytical grade (Merck, Cat. No. 42)

pyridine, analytical grade (Riedel de Haen, Cat. No. 33638)

acetic acid, analytical grade (Merck, Cat. No. 1.00063)

acetylating reagent: 810 ml of pyridine, 100 ml of acetic anhydride and9 ml of acetic acid

water, deionized

THF and toluene

b) Determination of the acid number (AN) 10 ml of toluene and 10 ml ofpyridine were added to about 1 to 1.5 g of accurately weighed testsubstance, and the mixture was then heated to 95° C. After a solutionwas obtained, it was cooled to room temperature and, after addition of 5ml of water and 50 ml of THF, titrated against 0.1 N of ethanolic KOHstandard solution.

The determination was repeated without test substance (blank sample)

The acid number was then determined using the following formula:

AN=c×t×56.1×(V1−V2)/m(in mg KOH/g)

where c = amount of substance concentration of the ethanolic KOHstandard solution in mol/l, t = titer of the ethanolic KOH standardsolution m = weight of test substace in mg V1 = ml of standard solutionused with test substance V2 = ml of standard solution used without testsubstance.

Reagents used:

ethanolic KOH standard solution, c=0.1 mol/l, titer =0.9913 (Merck, Cat.No. 9115)

pyridine, analytical grade (Riedel de Haen, Cat. No. 33638)

water, deionized

THF and toluene

c) Determination of the OH number

The OH number is obtained from the sum of the apparent OH number and theAN:

OH number=apparent OH number+AN

Abbreviations used:

DOC: dissolved organic carbon DMT: dimethyl terephthalate PCL:Polycaprolactone ® Tone P 787 (Union Carbide) PMDA: pyromelliticdianhydride AN: acid number TBOT: tetrabutyl orthotitanate VN: viscositynumber (measured in o-dichlorobenzene/phenol (50/50 ratio by weight) ata concentration of 0.5% by weight of polymer at 25° C. T_(m): meltingtemperature = temperature at which a maximum endothermic heat fluxoccurs (extreme of the DSC plots) T_(g): glass transition temperature(midpoint of the DSC plots)

The DSC measurements were carried out with a 912+Thermal Analyzer 990from DuPont. The temperature and enthalpy calibration was carried out ina conventional way. The sample typically weighed 13 mg. The heating andcooling rates were 20 K/min unless other-wise indicated. The sampleswere measured under the following conditions: 1. heating run on samplesin the state as supplied, 2. rapid cooling from the melt, 3. heating runon samples cooled from the melt (samples from 2). The second DSC runs ineach case were used, after impressing a uniform thermal prehistory, tomake it possible to compare the various samples.

Preparation of the polyesters P1 Example 1

4672 kg of 1,4-butanediol, 7000 kg of adipic acid and 50 g of tindioctoate were reacted under a nitrogen atmosphere at a temperature inthe range from 230 to 240° C. After most of the water which had beenformed in the reaction had been removed by distillation, 10 g of TBOTwere added to the reaction mixture. After the acid number had fallenbelow 1, excess 1,4-butanediol was removed by distillation under reducedpressure until the OH number reached 56.

Example 2

384 g of 1,4-butanediol, 316 g of DMT and 1 g of TBOT were placed in athree-neck flask and heated to 180° C. while stirring slowly under anitrogen atmosphere. During this, the methanol formed in thetransesterification was removed by distillation. After addition of 101.6g of adipic acid, the mixture was heated to 230° C. while increasing thestirring speed under a nitrogen atmosphere over the course of 2 h, andthe water formed in the condensation reaction was removed bydistillation. Then, under a nitrogen atmosphere, 278 g of Pluriol E 600(polyethylene glycol with molecular weight 600 g/mol) and 0.5 g of TBOTwere added. The pressure was reduced stepwise to 5 mbar and then kept at<2 mbar at 230° C. for 1 h, during which the water formed in thecondensation reaction and the excess 1,4-butanediol were removed bydistillation.

OH number: 5 mg KOH/g

AN: 0.5 mg KOH/g

VN: 109.38 g/ml

T_(m) 127.5° C.

T_(g): −46° C. (DSC, state as supplied)

Enzyme test with Rhizopus arrhizus: ΔDOC: 72 mg/l; ΔDOC (PCL): 2,455mg/l

Example 3

384 g of 1,4-butanediol, 315.8 g of DMT, 710.5 g of Pluriol® E 1500(BASF, polyethylene glycol with molecular weight 1,500 g/mol) and 1 g ofTBOT were placed in a three-neck flask and heated to 180° C. whilestirring slowly under a nitrogen atmosphere. During this, the methanolformed in the transesterification was removed by distillation. Afteraddition of 101.6 g of adipic acid and 12 g of sodium sulfoisophthalate,the mixture was heated to 230° C. while increasing the stirring speedunder a nitrogen atmosphere over the course of 2 h, and the water formedin the condensation reaction was removed by distillation. Then, under anitrogen atmosphere, 1.3 g of PMDA and, after a further hour, 0.4 g of50% by weight aqueous phosphorous acid were added. The pressure wasreduced stepwise to 5 mbar and then maintained at <2 mbar at 230° C. for1 h, during which the water formed in the condensation reaction and theexcess 1,4-butanediol were removed by distillation.

OH number: 12 mg KOH/g AN: 0.8 mg KOH/g VN: 68.4 g/ml T_(m): 107.8° C.(DSC, state as supplied)

Example 4

2.5 kg of the polymer from Example 1, 5.6 kg of DMT, 5.6 kg of1,4-butanediol, 6.22 kg of Systol® T 122 (BASF, polyethylene glycol withmolecular weight 600 g/mol) and 20 g of TBOT were heated in a vessel to180° C. while stirring slowly under a nitrogen atmosphere. During this,the methanol formed in the transesterification was removed bydistillation. The mixture was heated to 230° C. while increasing thestirring speed over the course of 3 h and, after a further hour, 8 g of50% by weight aqueous phosphorous acid were added. The pressure wasreduced to 5 mbar over the course of 2 h and was then maintained at <2mbar at 240° C. for 1 h, during which the excess 1,4-butanediol wasremoved by distillation.

OH number: 4 mg KOH/g AN: 2.5 mg KOH/g VN: 107 g/ml T_(m): 111° C.T_(g): −47° C. (DSC, state as supplied)

Example 5

506.6 g of the polymer from Example 1, 1,359.3 g of DMT, 134 g of sodiumsulfoisophthalate, 1,025 g of 1,4-butanediol, 491 g of diethylene glycoland 3.5 g of TBOT were heated in a vessel to 180° C. while stirringslowly under a nitrogen atmosphere. During this, the methanol formed inthe transesterification and water were removed by distillation. Themixture was heated to 230° C. while increasing the stirring speed overthe course of 3 h and, after a further hour, 8 g of 50% by weightaqueous phosphorous acid were added. The pressure was reduced to 5 mbarover the course of 2 h and then maintained at <2 mbar at 240° C. for 1h, during which the excess 1,4-butanediol was removed by distillation.

OH number: 7 mg KOH/g AN: 1.9 mg KOH/g

Example 6

90 g of the polymer from Example 4 were heated with 60 g ofpolycaprolactone (PCL) and 0.75 g of pyromellitic dianhydride to 180° C.under a nitrogen atmosphere and stirred for 2 hours. Subsequently, 1.21g of hexamethylene diisocyanate were added over the course of 15 min,and the mixture was then stirred for 30 min.

Product before HDI addition:

VN: 148 g/ml

Product after HDI addition:

VN: 190 g/ml

Example 7

335 g of ethylene glycol, 64 g of diethylene glycol, 388 g of DMT, 2.6 gof pyromellitic dianhydride, 1 g of TBOT and 12 g of sodiumsulfoisophthalate were placed in a three-neck flask and heated to 180°C. while stirring slowly under a nitrogen atmosphere. During this, themethanol formed in the transesterification was removed by distillation.Then 75 g of adipic acid and 43.5 g of 91% by weight aqueous lactic acidwere added. The mixture was heated to 200° C. while increasing thestirring speed over the course of 2 h. The pressure was then reducedstepwise to 5 mbar and then maintained at <2 mbar at 210° C. for 1 h,during which the water formed in the condensation reaction and theexcess ethylene glycol were removed by distillation.

OH number: 15 mg KOH/g AN: 1.4 mg KOH/g

Example 8

335 g of ethylene glycol, 240 g of Lutrol® E 400 (BASF, polyethyleneglycol with molecular weight 400 g/mol), 388 9 of DMT and 1 g of TBOTwere placed in a three-neck flask and heated to 180° C. while stirringslowly under a nitrogen atmosphere. During this, the methanol formed inthe transesterification was removed by distillation. Then 75 9 of adipicacid and 43.5 g of 91% by weight aqueous lactic acid were added. Themixture was heated to 200° C. while increasing the stirring speed overthe course of 2 h. The pressure was then reduced stepwise to 5 mbar andthen maintained at <2 mbar at 210° C. for 1 h, during which the waterformed in the condensation reaction and the excess ethylene glycol wereremoved by distillation.

OH number: 20 mg KOH/g

AN: 0.3 mg KOH/g

T_(m): 135° C., (DSC, state as supplied)

Enzyme test with Rhizopus arrhizus: ΔDOC: 143 mg/l; ΔDOC (PCL): 1,989mg/l

Example 9

486.6 g of 1,4-butanediol, 240 g of Lutrol® E 400 (BASF, polyethyleneglycol with molecular weight 400 g/mol), 388 g of DMT, 3.1 9 of1,3,5-benzenetricarboxylic acid and 1 g of TBOT were placed in athree-neck flask and heated to 180° C. while stirring slowly under anitrogen atmosphere. During this, the methanol formed in thetransesterification was removed by distillation. Then 75 g of adipicacid and 43.5 g of 91% by weight aqueous lactic acid were added. Themixture was heated to 200° C. while increasing the stirring speed overthe course of 2 h. The pressure was then reduced stepwise to 5 mbar andthen maintained at <2 mbar at 210° C. for 1 h, during which the waterformed in the condensation reaction and the excess ethylene glycol wereremoved by distillation.

OH number: 14 mg KOH/g

AN: 0.3 mg KOH/g

Enzyme test with Rhizopus arrhizus: ΔDOC: 193 mg/l; ΔDOC (PCL): 1,989mg/l

Example 10

150 g of the polymer from Example 3 were heated to 180° C. under anitrogen atmosphere. Then, while stirring, 1.15 g of hexamethylenediisocyanate were added over the course of 15 min, and the mixture wasthen stirred for 30 min.

Product after HDI addition:

VN: 112 g/ml

We claim:
 1. A biodegradable polyether ester P2 produced by the processof reacting a mixture consisting essentially of (b1) a mixtureconsisting essentially of 20-95 mol % of adipic acid or ester-formingderivatives thereof or mixtures thereof, 5-80 mol % of terephthalic acidor ester-forming derivatives thereof or mixtures thereof, and 0 mol % ofa compound containing sulfonate groups, where the total of theindividual mole percentages is 100 mol %, (b2) a mixture of dihydroxycompounds (a2), consisting essentially of (a21) from 15 to 99.8 mol % ofa dihydroxy compound selected from the group consisting ofC₂-C₆-alkanediols and C₅-C₁₀-cycloalkanediols, (a22) from 85 to 0.2 mol% of a dihydroxy compound containing ether functionalities of theformula I HO—[(CH₂)_(n)—O]_(m)—H  I where n is 2, 3 or 4 and m is aninteger from 2 to 250, or mixtures thereof, where the molar ratio of(b1) to (b2) is chose in the range from 0.4:1 to 1.25:1, (b3) from 0.01to 100% by weight, based on component (b1), of a hydroxycarboxylic acidB1, and (b4) from 0 to 5 mol %, based on component (b1), of compound Dhaving at least three groups capable of ester formation, where thehydroxycarboxylic acid B1 is defined by the formulae IIa or IIb

where p is an integer from 1 to 1500 and r is an integer from 1 to 4,and G is a radical which is selected from the group consisting ofphenylene, —(CH₂)_(k)—, where k is an integer from 1 to 5, —C(R)H—and—C(R)HCH₂, where R is methyl or ethyl, where the polyether ester P2 hasa molecular weight (M_(n)) in the range from 5000 to 80,000 g/mol, aviscosity number in the range from 30 to 450 g/ml (measured ino-dichlorobenzene/phenol (50150 ratio by weight) at a concentration of0.5% by weight of polyether ester P2 at 25° C.) and a melting point inthe range from 50 to 235° C.
 2. A biodegradable polyether ester P2defined in claim 1, wherein the compound D is a member selected from thegroup consisting of tartaric acid, citric acid, malic acid,trimethylolpropane, trimethylolethane, pentaerythritol, polyerythritol,polyethertriol, glycerol, trimesic acid, trimellitic acid, trimelliticanhydride, pyromellitic acid, pyromellitic dianhydride, orhydroxyisophthalic acid.
 3. A biodegradable polyether ester P2 definedin claim 1, wherein the compound D is malic acid.
 4. A biodegradablepolyether ester P2 defined in claim 1, wherein the compound D is apolyethertriol.
 5. A biodegradable polyether ester P2 defined in claim1, wherein the compound D is glycerol.
 6. A biodegradable polyetherester P2 defined in claim 1, wherein the compound D is pyromellitic acidor pyromellitic diianhydride.
 7. A biodegradable polyether ester P2defined in claim 1, erein the compound D is selected from the groupconsisting of 4-carboxyphthalic anhydride, 1, 3, 5-benzenetricarboxylicacid, pentaerythritol and polyethertriols.
 8. A biodegradable polyetherester P2 defined in claim 1, wherein the polyester P2 comprises at least0.05 mol %, based on (a₁), of the compound D.
 9. A biodegradablepolyether ester P1 defined in claim 1, wherein P1 is obtained byinitially reacting a part of the component (a₁) and a part of thecomponent (a₂) to form a prepolymer, and subsequently reacting theprepolymer with the residual part of the component (a₁), the residualpart of component (a2) and with the component (a3).
 10. A biodegradablepolyether ester P1 defined in claim 1, wherein P1 is obtained byreacting the components (a₁), (a₂) and (a₃) in the presence ofphosphonous acid or phosphorous acid.
 11. A biodegradable polyetherester P1 defined in claim 9, wherein P1 is obtained by reacting theprepolymer with the residual part of the component (a₁), the residualpart of the component (a₂) and with the component the component (a₃) inthe presence of phosphonous acid or phosphorous acid.